Evaluation of electric motor concepts for large marine Azipod propulsion units

Abstract

This thesis investigates various electric motor types suitable for high-power, low-speed marine propulsion systems, with a particular focus on their application in Azipod propulsion units. Azipod systems, used for their high manoeuvrability and efficiency, require propulsion solutions that can deliver high torque at low rotational speeds while maintaining reliability and energy efficiency. The study begins with a brief review of motor technologies including permanent magnet synchronous motors (PMSM), induction motor (IM) and synchronous reluctance motors (SynRM). Initial design was implemented analytically, and the detailed design is conducted by finite element analysis (FEA) using Ansys Motor-CAD software. The findings highlight the importance of optimizing motor design parameters such as air gap, slot geometry, and magnetic properties to achieve the required performance. Finally, based on the estimated FEA results, the comparative analysis was performed. The thesis concludes that the most suitable motor configuration for large-scale marine Azipod propulsion systems is the Permanent Magnet Synchronous Motor, due to its superior efficiency and performance. The Synchronous Reluctance Motor ranks next in efficiency and, with certain design modifications, could also be a viable option. The Induction Motor, however, demonstrates the lowest efficiency for this specific application, making it the least favourable choice among the three.